With less than three weeks until Georgia's Republican Senate primary, Rep. Jack Kingston, R-Ga., released an internal poll Thursday that found him leading the crowded field .

Kingston led with 20 percent, followed by former Dollar General and Reebok CEO David Perdue with 17 percent, former Georgia Secretary of State Karen Handel with 14 percent, Rep. Phil Gingrey with 13 percent and Rep. Paul Broun with 8 percent. Twenty-eight percent of voters were undecided.

The primary is essentially a race to finish in the top two. If no candidate receives a majority of the primary vote, the two leading vote recipients will advance to a July 22 runoff. The winner is expected to face former Points of Light Foundation CEO Michelle Nunn in the general election for the seat of retiring GOP Sen. Saxby Chambliss. The poll, conducted by McLaughlin & Associates, found that 43 percent of likely Republican primary voters had a favorable opinion of Kingston , compared to 12 percent with an unfavorable opinion. He had the highest favorables of the five candidates polled and the highest net positive rating.

The poll surveyed 400 likely Republican primary voters April 28-29 using live telephone interviews on both land lines and cell phones. It had a 4.9-point margin of error.

The poll was released Thursday afternoon shortly after a robo-poll found Kingston in third place, behind Perdue, at 22 percent, and Handel, at 21 percent. Kingston was at 17 percent. That poll was conducted by InsiderAdvantage for Morris News and Fox5.

Handel has gained momentum heading into the May 20 primary, but Kingston is the recipient of a large ad buy from the U.S. Chamber of Commerce. On Wednesday, the Kingston campaign began a six-figure buy behind an ad in which his children tout his cheapness.

The general-election race is rated Favored Republican by the Rothenberg Political Report/Roll Call.